Given that they're all probably not disabled, I'm wondering what grounds they have to sue in the first place.
I would imagine that most lawyers that file legitimate ADA lawsuits aren't disabled. They file them on behalf of someone who is. From the article:
Hansmeier registered the Disability Support Alliance in Minnesota in July 2014 and listed himself as the nonprofit's agent. Its members, all of whom live with a disability, include Wong, of Minneapolis, and three Marshall residents.
He's finding disabled people who get paid to complain, creating the "legitimacy" of the ADA complaint. According to the article, Minnesota in their infinite wisdom made it possible for a plaintiff to file criminal misdemeanor charges against someone for ADA violations with penalties up to 90 days in jail and up to a $1000 fine.
The goal should always be about accessibility to all, not making money through settlements because of inconvenience. Only the most egregious cases of non-compliance should result in any criminal charges, and even then it shouldn't be done on the behalf of the filing plaintiff.